nxt.http

Class EventWait

java.lang.Object

nxt.http.APIServlet.APIRequestHandler

nxt.http.EventWait

public class EventWait
extends APIServlet.APIRequestHandler

The EventWait API will wait for one of the server events registered by EventRegister. EventWait will return immediately if one or more events have occurred since the last time EventWait was called. All pending events will be returned in a single response. The events remain registered so successive calls to EventWait can be made without another call to EventRegister.

Request parameters:

• token - Event registration token returned by the EventRegister API.
• timeout - Number of seconds to wait for an event. The EventWait will complete normally if no event is received within the timeout interval. nxt.apiEventTimeout will be used if no timeout value is specified or if the requested timeout is greater than nxt.apiEventTimeout.

Response parameters:

• events - An array of event objects

Error Response parameters:

• errorCode - API error code
• errorDescription - API error description

Event object:

• name - The event name
• ids - An array of event object identifiers

Event names:

• Block.BLOCK_GENERATED
• Block.BLOCK_POPPED
• Block.BLOCK_PUSHED
• Ledger.ADD_ENTRY.account - Monitor changes to the specified account. 'account' may be the numeric identifier or the Reed-Solomon identifier of the account to monitor for updates. All accounts will be monitored if no account is specified. Specifying an account identifier of 0 is the same as not specifying an account.
• Peer.ADD_ACTIVE_PEER
• Peer.ADD_PEER
• Peer.BLACKLIST
• Peer.CHANGE_ACTIVE_PEER
• Peer.CHANGE_ANNOUNCED_ADDRESS
• Peer.CHANGE_SERVICES
• Peer.REMOVE_PEER
• Peer.UNBLACKLIST
• Transaction.ADDED_CONFIRMED_TRANSACTIONS.account (omit account to monitor all accounts)
• Transaction.ADDED_UNCONFIRMED_TRANSACTIONS.account (omit account to monitor all accounts)
• Transaction.REJECT_PHASED_TRANSACTION.account (omit account to monitor all accounts)
• Transaction.RELEASE_PHASED_TRANSACTION.account (omit account to monitor all accounts)
• Transaction.REMOVED_UNCONFIRMED_TRANSACTIONS.account (omit account to monitor all accounts)

Event object identifiers:

• Block string identifier for a Block event
• Peer network address for a Peer event
• Transaction chain and full hash for a Transaction event as a string in the format 'chain:hash'

Method Summary

Modifier and Type	Method and Description
protected boolean	allowRequiredBlockParameters()
protected boolean	isChainSpecific()
protected org.json.simple.JSONStreamAware	processRequest(javax.servlet.http.HttpServletRequest req) Process the EventWait API request The response will be returned immediately if there are any pending events.
protected boolean	requirePost()

Methods inherited from class nxt.http.APIServlet.APIRequestHandler

canHaveRecipient, getAPITags, getCreateTransactionTypes, getFileParameters, getParameters, getSensitiveParameters, isIgnisOnly, isTextArea, processRequest, requireBlockchain, requiredBlockUpdateLock, requireFullClient, requirePassword, startDbTransaction

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

processRequest

protected org.json.simple.JSONStreamAware processRequest(javax.servlet.http.HttpServletRequest req)
                                                  throws ParameterException

Process the EventWait API request The response will be returned immediately if there are any pending events. Otherwise, an asynchronous context will be created and the response will be returned after the wait has completed. By using an asynchronous context, we avoid tying up the Jetty servlet thread while waiting for an event.

Specified by:

processRequest in class APIServlet.APIRequestHandler

Parameters:

req - API request

Returns:

API response or null

Throws:

ParameterException - Invalid parameter specified

requirePost

protected final boolean requirePost()

Overrides:

requirePost in class APIServlet.APIRequestHandler

allowRequiredBlockParameters

protected boolean allowRequiredBlockParameters()

Overrides:

allowRequiredBlockParameters in class APIServlet.APIRequestHandler

isChainSpecific

protected boolean isChainSpecific()

Overrides:

isChainSpecific in class APIServlet.APIRequestHandler